Dating back to May when I first heard about it I lodged a complaint, went back and forth about 5 times then nothing until August. Got the text saying £5 on 17 August, sent in letter, wasn't received, sent in recorded letter on 24 August that was received the next day, then sent daily emails to director's office, phoned customer services once every 3 days, recorded the calls, sent them to the director's office pointing out mistakes, really invested some effort into it. I was free by 2 September, so 9 days from my recorded letter being acknowledged.

You have to make a real nuisance of yourself to get it done so quickly though. Start recording calls and sending them to director's office, tell them you are recording them all so you can use them with a third party at a later date (I threatened to publish mine online for all to hear).